Catch patterns of the German Baltic Sea trawl fleet targeting demersal species between 2006 and 2009

Background. The data collection of commercial fisheries has been formalized by the EU data collection framework (DCF). Besides gaining relevant information to fisheries management under the Common Fisheries Policy, the data of the DCF will gain importance in assessing the impacts of fishing on the ecosystem of the Baltic Sea. Materials and methods. The catch of the demersal German Baltic Sea trawl fleet between 2006 and 2009 was sampled by on-board observers to investigate the temporal and spatial patterns in catch composition. Results. There was a general increment in tow duration, landing weights, and discard weights from west to east. The most important species by catch weight was cod, for which highest catches were obtained during spring in ICES subdivision 25. Single hauls exceeded 25 h and caught more than 9900 kg of cod. On average, about 5%, 13%, and 20% and of the captured cod, flounder, and dab, respectively, were discarded. Conclusion. The presently reported study provides a benchmark for the German Baltic Fisheries that can be used for assessment of new management regulations and/or new marine policies. A comprehensive documentation of the spatial and temporal catch distribution of the German Baltic demersal trawl fleet, prior to the implementation of marine spatial planning measures such as marine protected areas or offshore wind farms, should help to evaluate the implications of intensifying spatial use on the fishing industry

A review on herring, Clupea harengus (Actinopterygii: Clupeiformes: Clupeidae) recruitment and early life stage ecology in the western Baltic Sea

Herring, Clupea harengus L., is an important commercial fish species in the Baltic Sea region since medieval times. The western Baltic spring spawning herring (WBSS) is one of three major Baltic Sea herring stocks, supporting a significant over-regional fishery in the western Baltic Sea as well as in the Kattegat and Skagerrak area. One major component spawns in the vicinity of the German island of Rügen and the associated major spawning ground, the Greifswalder Bodden (GWB), a shallow, semi-enclosed sub-system of estuarine character. Research of herring biology and ecology has an extensive history in the area probably due to the long fishery tradition and the importance of this particular herring stock for the local Baltic coast economy. In this review most of the scientific findings about WBSS in its spawning areas, mainly the GWB, is summarized. This study is based on critical review of over 120 publications and scientific sources from the past 100 years containing relevant information on possible consequences of multiple environmental and anthropogenic induced stressors of herring recruitment and productivity. Besides current peer reviewed literature a significant amount of grey literature was included, consisting primarily of papers and reports written in German language and representing the only historical data sources and published documentation of regional western Baltic herring ecology

Marking otoliths of Baltic cod (Gadus morhua Linnaeus, 1758) with tetracycline and strontium chloride

Identified were suitable dosages of tetracycline hydrochloride (TET) in three single treatments and three combined treatments of TET with 2 mg/kg strontium chloride (STR) in wild western Baltic cod (Gadus morhua), in terms of (a) obtainable mark qualities (visibility of fluorescent bands), (b) growth assessment, and (c) induced mortality rates. Isotonic NaCl solution was injected in a control group (25 cod per treatment). The results provide the basis for imperative age validation studies of Baltic Sea cod. Cod originating from pound nets near Fehmarn Island were kept in swimming net cages at the harbor of Warnemunde for 1.5 months. Mean initial total length was 28(+/- 3) cm (salinity: 13, water temperature: 13 to 8 degrees C). Overall average growth of surviving cod was 0.8 mm/day. In single TET treatments, lowest mortality rates and best mark quality were observed for TET concentrations of 100 compared to 50 and 25 mg/kg wet mass. Mortality rates of the 100 mg/kg treatment group were remarkably lower than in the control group emphasizing the antibiotic effect of TET. By contrast, the double treatment in the TET-STR groups resulted in a binding interaction between both markers in the fish body causing either the antibiotic potency being inhibited or TET and STR forming a non-beneficial chelate (increased mortality), and decreased incorporation of TET in the otolith (reduced visibility of TET bands). Consequently, TET (short-term marker) and STR (long-term marker) should not be injected together. Our results demonstrate that the binding interactions between these substances known from homoiotherm animals also apply for poikilotherms such as fish

WebGR – storing images of biological material and creating a framework to promote the implementation of sound statistical analysis in age calibration

The objective of the WebGR project is to develop a set of web services to support the organisation and data analysis of calibration workshops, both for age and maturity information, implemented in a coherent tool installable as a website. The website consists of a repository of images, a set of web forms to run a calibration exercise online, a reporting module with the most common statistical analysis and import/export modules to manage images and results. The software has a creative commons license (Open Source) to promote transparency, technology transfer and peer review; and will allow the scientific community to get involved in further developments, like linkage to statistical analysis engines, or any other specific features. The usage of WebGR to carry out calibration workshops will promote the application of sound statistical analysis to design the experiment and compute workshop results. The results are extracted in a standard format that can be easily sent to scientists doing assessments. Keywords: WebGR, calibration workshops, age, maturit

Workshop on the Further Development of the New IBTS Gear (WKFDNG). ICES Scientific Reports. 4:18

The standard gear for the International Bottom Trawl Survey (IBTS), a fisheries-independent research survey originating from the 1960s, will be replaced. The long-term monitoring pro-vides data on commercial pelagic and demersal fish species for stock assessments and facili-tates examination of changes in fish distribution and abundance. The remit of this Workshop on the Further Development of the New IBTS Gear (WKFDNG) was to design a simple gear, as standardised as possible, robust, and easy to maintain. Additionally, the workshop was tasked to provide input for the roadmap towards implementation of the new gear